How about using Excel to keep track of your hours and a mail-merge in Word to print or email the invoices? Assuming you already use those programs for your consulting activities it's free.
Am just starting out with my business, just moved away from serving big organizations and started a consulting firm. I have got a few clients whom I need to invoice every week.
It's a pain to use a template as I am unable to keep track of things and it's a pain to be honest. Tried a few invoicing systems but the trial versions are over now and they are a bit on the complex & expensive side. Looking for something around $5 - 10 per month range.
I'd prefer cloud based, not wanting a desktop based version.